There are many computer-like devices that have no keyboards or only limited keypads, but still require text entry. One example of such a device is a so-called "Internet TV" device that enables a user to browse the World Wide Web of the Internet using a television and a simple infrared (IR) remote control. Another ii example is a video game device. Both of these devices are used in conjunction with CRT's or other two-dimensional graphical displays, while neither device has a full alphanumeric keyboard.
Typically, control buttons available to the user are limited to directional control keys and some variation of an "action" key. The directional control keys are used to move a cursor or focus to various locations on a display, and the action key is used to select an action corresponding to the cursor or focus location. Typically, these keys are used to enter numbers and text.
FIG. 1 illustrates one method of on-screen text entry that utilizes a "spin dial" 10. A spin dial has a small box 11 containing a symbol that can be changed by the user. Up and down arrows 12 and 13 are displayed on the top and bottom of the box. The user can position a cursor over the up and down arrows and press an action key to change the displayed symbol. For instance, pressing the action key when the cursor is positioned over the up arrow changes the displayed symbol to the next in a sequence of symbols--from A to B, for example. Similarly, pressing the action key when the cursor is positioned over the down arrow changes the displayed symbol to the preceding symbol in the sequence.
FIG. 2 illustrates another method of text entry, utilizing a "virtual keyboard" 15. The virtual keyboard is actually an on-screen representation of a conventional QWERTY keyboard such as implemented in typewriters and computer keyboards. To select a particular character, the user moves the cursor to that character and presses the action key. A "done" key indicates the end of text entry.
Although these prior art methods are workable, they are awkward and burdensome. Each method requires significant concentration on the part of the user, and a significant number of key depressions in order to enter even very simple text strings. Compared to handwriting and typing, with which most users are comfortable, these prior art methods are quite difficult.
Handwriting recognition has been used in some contexts to reduce or eliminate reliance on bulky keyboards. In the past, however, handwriting recognition has been a difficult proposition, requiring very complex software and correspondingly expensive hardware.
To reduce the complexity normally required of handwriting recognition systems, many devices such as the Graffiti recognition system, part of the PalmPilot.TM. organizer sold by Palm Computing, Inc, a subsidiary of 3COM Corp., require users to learn new character symbols that are somewhat artificial. These character symbols are designed to reduce the ambiguity and variability associated with normal handwriting, and to thus reduce the amount of analysis required to process written characters. Even with these measures, significant processing is required to convert highly variable user pen strokes to alphanumeric characters.
The invention described below allows a user to enter characters by tracing them with a fingertip. In contrast to many prior art handwriting recognition systems, traced character decoding is very simple. Furthermore, users are not constrained to unnatural character or symbol shapes when tracing characters. The invention is particularly adaptable for use with a wireless remote control, in which processing capacity is normally very limited. The invention allows tracing on a smaller device, and permits operation without requiring the user to look at the device. This is especially beneficial in a living-room setting where television-based devices are used.